Charlotte Caldwell announced she would be 'openly smuggling' it in protest against the UK’s drug laws.

Immigration authorities have confiscated potentially life-saving cannabis medication after a mother and her epileptic son returned from a 7,000 mile weekend round trip to collect it.

Charlotte Caldwell bought the cannabis oil – which keeps her sick son seizure free – legally in Canada and announced she would be “openly smuggling” it into the UK in protest against the UK’s drug laws.

Twelve-year-old Billy Caldwell made history when he became the first UK recipient of an NHS prescription for cannabis.

Without the drug, he has up to 100 potentially fatal seizures a day but last week the Home Office told his family doctor to stop giving out the drug or face disbarment.

On Thursday, a day before the family’s supply ran out, Caldwell took the dramatic decision to fly to Toronto to get more.

The medication was confiscated at London’s Heathrow airport by officials who said it is not certified for use in the UK.

“I’m just going to turn around and go get some more; and keep doing so until the UK authorities see sense. I take the view that I’d rather have my son illegally alive than legally dead. This is the scenario that the phrase ‘no brainer’ was invented for,” said Caldwell.

Conservative MP Dan Poulter, who is a doctor and who has been supporting the Caldwells, said: “The current law is ridiculous; there is growing evidence that cannabis products used medically can be helpful in treating a number of conditions, but yet is still seen through the prism of illegality here in the UK.”

He said it was inhumane to confiscate the medication when it is legal in so many other countries.

He added: “This is bound to have a devastating effect on Billy and his family and I will continue to do all that I can to help bring about this much needed change in our law.”

Ms Caldwell, from Castlederg in Co Tyrone, told a press conference at Heathrow: “It’s Billy’s anti-epileptic medication ... it’s not some sort of joint full of recreational cannabis, it is his anti-epileptic medication that he has taken off me at the airport today.

“I will just go back to Canada and get more and I will bring it back again because my son has a right to have his anti-epileptic medication in his country, in his own home.

“Let me tell you something now: we will not stop, we are not going to stop, we are not going to give up, we have love, hope, faith for our kids and we are going to continue.”

She said she will be meeting Mr Hurd at the Home Office this afternoon to plead to get the oil back.